|
C
|
oronaviruses
are types of viruses that typically affect the respiratory tracts of birds and
mammals, including humans. Doctors associate them with the common cold,
bronchitis, pneumonia, and severe acute respiratory syndrome (SARS), and they
can also affect the gut.
These
viruses are typically responsible for common colds more than serious diseases.
However, coronaviruses are also behind some more severe outbreaks.
Over the last 70 years,
scientists have found that coronaviruses can infect mice, rats, dogs,
cats, turkeys, horses, pigs, and cattle. Sometimes, these animals
can transmit coronaviruses to humans.
Stay informed with live updates on the current COVID-19 outbreak.
Most recently, authorities
identified a new coronavirus outbreak in China that has now reached other
countries. It has the name coronavirus disease 2019, or COVID-19.
In this article, we explain
the different types of human coronaviruses, their symptoms, and how people
transmit them. We also focus on three particularly dangerous diseases that have
spread due to coronaviruses: COVID-19, SARS, and MERS.
Share on PinterestCovering
the mouth when sneezing may help stop the spread of coronaviruses.
Researchers first isolated a coronavirus in 1937.
They found a coronavirus responsible for an infectious bronchitis virus
in birds that had the ability to devastate poultry stocks.
Scientists first found
evidence of human coronaviruses (HCoV) in the 1960s in the noses of people with
the common cold. Two human coronaviruses are responsible for a large proportion
of common colds: OC43 and 229E.
The name “coronavirus”
comes from the crown-like projections on their surfaces. “Corona” in Latin
means “halo” or “crown.”
Among humans, coronavirus
infections most often occur during the winter months and early spring. People regularly become ill
with a cold due to a coronavirus and may catch the same one about 4 months
later.
This is because coronavirus
antibodies do not last for a long time. Also, the antibodies for one strain of
coronavirus may be ineffective against another one.
Cold- or flu-like symptoms
usually set in from 2–4 days after a coronavirus infection and are typically
mild. However, symptoms vary from person-to-person, and some forms of the virus
can be fatal.
Symptoms include:
- sneezing
- runny nose
- fatigue
- cough
- fever in
rare cases
- sore throat
- exacerbated asthma
Scientists cannot easily
cultivate human coronaviruses in the laboratory unlike the rhinovirus, which is
another cause of the common cold. This makes it difficult to gauge the impact
of the coronavirus on national economies and public health.
There is no cure, so
treatments include self-care and over-the-counter (OTC) medication. People can
take several steps, including:
- resting and avoiding overexertion
- drinking enough water
- avoiding smoking and smoky areas
- taking acetaminophen, ibuprofen, or naproxen for pain
and fever
- using a clean humidifier or cool mist vaporizer
A doctor can diagnose the
virus responsible by taking a sample of respiratory fluids, such as mucus from
the nose, or blood.
MEDICAL NEWS TODAY NEWSLETTER
Stay in the know. Get our free daily newsletter
Expect in-depth,
science-backed toplines of our best stories every day. Tap in and keep your
curiosity satisfied.
Enter your email
SIGN
UP NOW
Your privacy is important to us
Coronaviruses belong to the
subfamily Coronavirinae in
the family Coronaviridae.
Different types of human
coronaviruses vary in how severe the resulting disease becomes, and how far
they can spread.
Doctors currently recognize
seven types of coronavirus that can infect humans.
Common types include:
- 229E (alpha coronavirus)
- NL63 (alpha coronavirus)
- OC43 (beta coronavirus)
- HKU1 (beta coronavirus)
Rarer strains that cause
more severe complications include MERS-CoV, which causes Middle East
respiratory syndrome (MERS), and SARS-CoV, the virus responsible
for severe acute respiratory syndrome (SARS).
In 2019, a dangerous new
strain called SARS-CoV-2 started circulating, causing the disease COVID-19.
Limited research is
available on how HCoV spreads from one person to the next.
However, researchers
believe that the viruses transmit via fluids in the respiratory system, such as
mucus.
Coronaviruses can spread in
the following ways:
- Coughing and sneezing without covering the mouth can
disperse droplets into the air.
- Touching or shaking hands with a person who has the
virus can pass the virus between individuals.
- Making contact with a surface or object that has the
virus and then touching the nose, eyes, or mouth.
- Some animal coronaviruses, such as feline coronavirus
(FCoV), may spread through contact with feces. However, it is unclear whether this
also applies to human coronaviruses.
The National Institutes of
Health (NIH) suggest that several groups of people have the
highest risk of developing complications due to COVID-19. These groups include:
- young children
- people aged 65 years or older
- women who are pregnant
Coronaviruses will infect
most people at some time during their lifetime.
Coronaviruses can mutate
effectively, which makes them so contagious.
To prevent transmission,
people should stay at home and rest while symptoms are active. They should also
avoid close contact with other people.
Covering the mouth and nose
with a tissue or handkerchief while coughing or sneezing can also help prevent
transmission. It is important to dispose of any tissues after use and maintain
hygiene around the home.
In 2019, the Centers for
Disease Control and Prevention (CDC) started monitoring the outbreak of a new coronavirus,
SARS-CoV-2, which causes the respiratory illness now known as COVID-19.
Authorities first identified the virus in Wuhan, China.
More than 74,000 people have contracted the
virus in China. Health authorities have identified many other people with
COVID-19 around the world, including many in the United States. On January 31,
2020, the virus passed from one person to another in the U.S.
The World Health
Organization (WHO) have declared a public health emergency relating to
COVID-19.
Since then, this strain has
been diagnosed in several U.S. residents. The CDC have advised that it is likely to spread to more people.
COVID-19 has started causing disruption in at least 25 other countries.
The first people with
COVID-19 had links to an animal and seafood market. This fact suggested that
animals initially transmitted the virus to humans. However, people with a more
recent diagnosis had no connections with or exposure to the market, confirming
that humans can pass the virus to each other.
Information on the virus is
scarce at present. In the past, respiratory conditions that develop from coronaviruses,
such as SARS and MERS, have spread through close contacts.
On February 17, 2020, the
Director-General of the WHO presented at a media briefing the following updates on how often the
symptoms of COVID-19 are severe or fatal, using data from 44,000 people with a
confirmed diagnosis:
|
Stage of severity
|
Rough percentage of people with COVID-19
|
|
Mild
disease from which a person can recover
|
More
than 80%
|
|
Severe
disease, causing breathlessness and pneumonia
|
Around
14%
|
|
Critical
disease, including septic shock, respiratory failure, and the failure of more
than one organ
|
About
5%
|
|
Fatal
disease
|
2%
|
The Director-General also
noted that the risk of serious complications increases with age. According to
the WHO, few children get COVID-19, although they are still investigating the
reasons for this.
However, while some viruses
are highly contagious, it is less clear how rapidly coronaviruses will spread.
Symptoms vary from person-to-person with
COVID-19. It may produce few or no symptoms. However, it can also lead to
severe illness and may be fatal. Common symptoms include:
- fever
- breathlessness
- cough
It may take 2–14 days for a
person to notice symptoms after infection.
No vaccine is currently available for
COVID-19. However, scientists have now replicated the virus. This could allow
for early detection and treatment in people who have the virus but are not yet
showing symptoms.
SARS was a contagious
disease that developed after infection by the SARS-CoV coronavirus. Typically,
it led to a life threatening form of pneumonia.
During November 2002, the
virus started in the Guangdong Province in southern China, eventually reaching
Hong Kong. From there, it rapidly spread around the world, causing infections
in more than 24 countries.
SARS-CoV can infect both
the upper and lower respiratory tracts.
The symptoms of SARS
develop over the course of a week and start with a fever. Early on in the
condition, people develop flu-like symptoms, such as:
- dry coughing
- chills
- diarrhea
- breathlessness
- aches
Pneumonia, a severe lung
infection, usually develops. At its most advanced stage, SARS causes failure of
the lungs, heart, or liver.
According to the CDC,
authorities marked 8,098 people as having contracted
SARS. Of these, 774 infections were fatal. This equates to a mortality rate of
9.6%.
Complications were more
likely in older adults, and half of all people over 65 years of
age who became ill did not survive. Authorities eventually controlled SARS in
July 2003.
MERS spread due to the
coronavirus known as MERS-CoV. Scientists first recognized this severe
respiratory illness in 2012 after it surfaced in Saudi Arabia. Since then, it
has spread to other countries.
The virus has reached the
U.S., while the largest outbreak outside the Arabian Peninsula occurred in
South Korea in 2015.
Symptoms of MERS include
fever, breathlessness, and coughing. The illness spreads through close contact
with people who already have an infection. However, all cases of MERS have
links to individuals recently returning from travel to the Arabian Peninsula.
No comments:
Post a Comment